Pharyngeal arch

Pharyngeal arches are embryological structures that contribute to the formation of the face, neck, and head in vertebrates. They are also known as branchial arches, visceral arches, or gill arches.

Development

The pharyngeal arches develop in a craniocaudal (head to tail) sequence during the fourth week of embryogenesis. Each arch is composed of a core of mesoderm, which is covered externally by ectoderm and internally by endoderm. The mesoderm within each arch gives rise to a cartilage element, a muscle element, and a nerve element.

Components

Each pharyngeal arch contains a cartilaginous structure, a cranial nerve, an arterial system, and muscular components. The cartilaginous structures form the skeletal structures of the face and neck. The cranial nerves provide sensory and motor innervation to the structures derived from each arch. The arterial systems become the major arteries of the head and neck.

Pharyngeal pouches

Between each pharyngeal arch is a pharyngeal pouch. The pharyngeal pouches are outpocketings of the endoderm-lined pharyngeal cavity. They meet with the ectoderm-lined pharyngeal clefts to form the pharyngeal membranes.

Clinical significance

Abnormal development of the pharyngeal arches can lead to a variety of congenital disorders. These include Pierre Robin sequence, Treacher Collins syndrome, and DiGeorge syndrome.

See also

• Pharyngeal pouch
• Pharyngeal groove
• Pharyngeal membrane

References

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